Project Summary Lung cancer is the leading cause of cancer mortality among American Indians and Alaska Natives (AI/AN), and AI/AN have worse lung cancer incidence rates, survival, and death compared to the general population. Because lung cancer screening (LCS) with low-dose computed tomography (LDCT) has been shown to reduce lung cancer mortality by roughly 20%, the United States Preventive Services Task Force now recommends LCS for men and women aged 55-80 years who meet specific eligibility criteria (grade-B evidence), and subsequently the Center for Medicare and Medicaid Services (CMS) opted to cover this test. However, the uptake of LCS implementation has been slow in most healthcare systems, and LCS implementation among AI/AN has never been studied. To address this knowledge and implementation gap, we prose the ?Tribally Engaged Approaches to Lung Screening (TEALS)? study, which is a collaborative effort between the Choctaw Nation of Oklahoma, the Stephenson Cancer Center, and the University of Oklahoma Health Sciences Center that directly addresses the low uptake of LCS in tribal settings through the development of a theory-driven LCS implementation program within the Choctaw Nation Health Services Authority (CNHSA). Over the course of 5 years, TEALS will: 1) Conduct focus groups and semi-structured interviews with CNHSA patients, clinicians, and health administrators to elucidate individual- and system-level barriers and facilitators that affect the implementation of LCS; 2) Develop, and iteratively refine an LCS care coordination intervention that will identify eligible persons for LCS, help these patients navigate the screening process, and link them with smoking cessation services, when applicable; 3) Measure the impact of the TEALS intervention on the receipt of screening and a set of patient- and practice-level outcomes by conducting a cluster-randomized clinical trial of LCS implementation; and 4) Disseminate the TEALS program to other researchers and healthcare systems that serve AI/AN patients. TEALS will bridge the gap between evidence and clinical practice for LCS in a high- need, low-resource setting by intervening at the level of the healthcare system. System-level interventions for guideline implementation tend to be understudied compared to those evaluating individual-level, behavioral interventions. However, the careful development and evaluation of an LCS screening program at the level of the healthcare system would be critical to ensure that more patients can receive LCS when appropriate. Through TEALS, our research will create a critically needed platform from which future studies could be launched that will examine how to tailor the application of the LCS guideline to the individual preferences of AI/AN patients. TEALS will establish an effective LCS program in a tribal system and thus provide a direct benefit to the Choctaw Nation by increasing LCS participation. TEALS will serve as a blueprint for establishing a sustainable and accessible infrastructure for LCS in AI/AN and other community health systems. By increasing screening for early stage lung cancer, TEALS could ultimately reduce lung cancer mortality in AI/AN communities, many of which are in great need of effective strategies to reduce longstanding cancer disparities.